Refractometer Flashcards
What is a refractometer?
-it measures the refractive index of a solution
What is refraction?
It is the bending of light rays as they pass from one medium into another medium with a different optical density
What is the degree of refraction?
It is related to the concentration of solid material in the medium (total solids of a solution)
How do you calibrate a refractometer?
They are calibrated using distilled water at a temp of 60-100 degrees F that would have a zero reading
Why is distilled water used to calibrate a refractometer?
Because no solution can be more dilute or have a lower concentration of dissolved solids than distilled water
The wide range of temperature of distilled water to be used ensures _________.
Reliability
This is why even when the refractometer is held in warm hands, it won’t skew the results
A refractometer is used to determine ….
1) the specific gravity of urine and other fluids
2) the protein concentration of plasma or other fluids
How to use a refractometer
1) inspect + clean the prism cover glass and cover plate
2) place a drop of sample fluid on prism cover glass then close the cover plate
3) point the refractometer toward a bright artificial light or sunlight
4) bring the light dark boundary line into focus by turning the eyepiece (all are focusable)
5) read + record result w/ appropriate scale (SG/protein)
6) clean the refractometer according to manufacturers recommendations (most recommend cleaning w/ distilled water and soft cloth)
Where do the scales on the refractometer normally sit?
Left hand side: total protein/solids
Right hand side: urine (specific gravity or urine concentration)
some have multiple scales
How to maintain a refractometer?
After each use, clean w/ water and dry
- distilled water is very ideal because there are no chemicals or minerals in it that could damage the prism
- when drying the refractometer, only a cloth designed for glass and lenses should be used. Regular paper towels & tissues can scratch the prism.
What do you do if the refractometer becomes cloudy? Why does it become cloudy?
It can become cloudy due to it being immersed in water and it can only be repaired by a professional
